This invention relates to polymer sealant compositions.
It is known to use polymers in sealant compositions. However, the whole field of sealant compositions is one of compromising between competing desirable properties. That is, changing a formulation to give improved properties in one area results in deterioration of some other property. For instance, it is desired that the sealant be flexible, i.e., rubbery, so as not to become brittle after a period of years and to allow for normal expansion and contraction. Rubbery materials are obviously ideally suited in their inherent characteristics in this regard. However, because of the unsaturation in rubber, it tends to become brittle on aging. It is readily apparent that it is desirable that the sealant adhere reasonably well to the sides of the joint or crack to which it is applied, yet after the sealent is cured it is undesirable for it to have a tacky exposed surface. Finally, it is desired that the sealant, in instances where a solvent base is used, have a relatively low bulk viscosity so as to facilitate the application; however, the use of increased percentages of solvent to achieve this low viscosity results in undesirable shrinkage when the solvent evaporates, once again an example of having to accept a deterioration in one property in order to get an improvement in another.